BRPI0616998B1 - additive composition, nucleating agent additive composition, polyolefin-based composition and method for producing a nucleated polymeric or polymeric composition - Google Patents

Abstract

silica-containing nucleating agent compositions and methods for using such compositions in polyolefins. The present invention relates to sorbitol and xylitol diacetals which are employed in polyolefins as nucleating agents. sorbitol and xylitol diacetals nucleating agents may be supplied in granular or powder form from polyolefin hoppers or mixing equipment during the formation of polymeric compositions and polymeric articles. The flow rate of sorbitol and xylitol diacetals is improved by the use of certain silicas at certain defined weight percentages. Silica compounds of the submicron size range can impart excellent flow enhancing properties when mixed and used with such diacetals.

Description

Report of the Invention Patent for "ADDITIVE COMPOSITION, ADDITIVE NUCLEATING AGENT COMPOSITION, POLYLEPHINE BASED COMPOSITION AND METHOD FOR PRODUCING A NUCLED POLYMERIC OR POLYMER COMPOSITION".

Background of the Invention Sorbitol acetals are employed in polyolefins as nucleating agents. Nucleating agents impart enhanced properties to polymers, including accelerated polymer crystallization and reduced turbidity. A widely used nucleating agent is 1,3-2,4 di (benzylidene) sorbitol (known as "DBS"), which is sold by Milli-ken & Company as a Millad® 3905 nucleating agent. Other sorbitol acetal compounds used as nucleating agents include: (1) bis (3,4-dimethylbenzylidene) sorbitol (sold by Milliken & Company as a nucleating agent of the Millad® 3988 brand, also known as "DMDBS"); and (2) bis (p-methylbenziidene) sorbitol, sold by Milliken & Company as a Millad® 3940 nucleating agent ("MDBS").

In polymer manufacturing and operations, sorbitol acetals may be supplied as an additive powder from a trough in polyolefin processing equipment to be mixed with the polymer. Commercial DMDBS in powder form is shown in Figure 1, and DMDBS crystal 9 is seen in the upper right of Figure 1.

Sorbitol acetals sometimes do not flow immediately or easily from such hoppers, which is an ongoing challenge for polymer additive equipment operators. Sorbitol acetals are inherently cohesive and compressible, which contributes to operational flow problems. Flow problems can manifest as bridging and clogging, which sometimes results in reduced flow or no flow at all. This is an operational problem for polymer blending operations. There are at least two common industry approaches to solving flow problems. The first approach employs pure sorbitol acetal powder with specially designed equipment and procedures to increase sorbitol acetal flow. Disadvantages of this approach include: (1) the design of special equipment can be expensive; and (2) it may not be practicable or practical to change procedures for adding sorbitol acetal to a production plant.

A second approach is to use a premix containing a selected sorbitol diacetal as a component and other additives in certain ratios. Premixes are usually provided in the form of pellets or agglomerated granules to improve flow properties. The literature presenting this approach includes: U.S. Patent No. 6,673,856 (Mentink), U.S. Patent No. 6,245,843 (Kobaiashi, et al.), And Korean Published Patent Application No. 2003-0049512 ("Kwun"). Operational flexibility can be sacrificed due to the fixed relationship between different additives. Such premixes may have negative effects on the optical performance of the resulting clarified polymer parts, such as splashes or undesirable white spots on polyolefin finished polymeric parts that have premixed sorbitol diacetals. The Kwun document describes a method of solving the flow and injection problems associated with sorbitol acetal nucleating agents through the use of organic lubricants. The Kwun document suggests coating the sorbitol acetal containing the compound with an organic material (ie "lubrication component"). The Kwun document specifically suggests the use of organic lubricants such as R-COOH acids, where R comprises C5-C22 carbon chain. "Metal soap" type coatings are recommended as the most effective coatings for such application. In one of the examples shown in the patent, a degree of hydrophilic Si02 in the micron size range was used in combination with an organic lubricating agent. What is needed in the industry is a way to improve the flow properties of particulate sorbitol acetals without the use of unwanted premixes, solvents, organic lubricants, and the like. A method and composition that can be applied without the addition of cumbersome and expensive mechanical equipment would be desirable. A composition or method of applying particulate sorbitol acetal compounds to polymers in such a manner as to result in uniform and uninterrupted flow of the hoppers should be highly desirable. A way to obtain high quality, low turbidity polymeric parts that are substantially free of undesirable stains or splashes would be highly desirable. The invention relates to the improved flow of sorbitol acetal compounds, and is described below.

Brief Description of the Drawings Figures 2 to 9 below illustrate various aspects of the invention, while Figure 1 shows the commercially known product. Figure 1 is a photomicrograph showing commercially known DMDBS clarifier crystals (Mil-lad brand clarifying agent 3988) of a DMDBS crystal size (length) of about 3 to 9 pm, such as the particle size. DMDBS 9 crystal; Figure 2 shows DMDBS combined with silica in the micron size range, where silica forms aggregates 16 which are often significantly larger than DMDBS 14 crystal particles; Figure 3 illustrates a photomicrograph of one embodiment of the invention of a submicron-sized silica DMDBS, wherein the submicron-sized silica particles are significantly smaller than the DMDBS 18 particle, and thus confer advantageous and beneficial properties. serve as a flow aid for the mixed DMDBS / silica additive composition; Figure 4 is a photomicrograph showing a DMDBS 18 particle of Figure 3 schematically comparing the size and configuration of the DMDBS 18 particle to submicron sized silica particle agglomerates 22, in which the silica particle size of submicron clusters form clusters 20a-c as shown in Figure 4; Figure 5 is a graph showing the cohesion force values for Examples 1-1 to 1-5, a charge level comparison for micron size range silica, including a comparative DMDBS without silica, such as also described herein; Figure 6 is a graph showing the cohesive force values for Examples 2-1 through 2-2; a comparison between hydrophobic and hydrophilic silica for silicon of micron size range, and as also described herein; Figure 7 is a graph showing the cohesive force values for Examples 2-1,2-2, 3-1 and 3-2 comparing submicron size, micron size, hydrophobic silica and hydrophilic as also described herein; and Figure 8 is a graph showing the cohesive force values for Examples 4-1 to 4-5 as also described herein; and Figure 9 is a graph showing the cohesive force values for Examples 5-1 and 5-2, which includes data on the effectiveness of the invention as applied to MDBS (bis (p-methylbenzylidene) sorbitol). Detailed Description of the Invention Reference will now be made to embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not as a limitation of the invention.

Submicron size range silica compounds having a reduced particle size have been found to confer excellent flow enhancing properties when mixed and used with the sorbitol acetal powder compounds.

In addition, it has been found that in many instances a hydrophobic silica mixed with the sorbitol acetal compounds confers enhanced flow properties for such a mixture as compared to mixtures using hydrophilic silica (ie Si02). In general, and especially for the micron size ranges, hydrophobic silica improves sorbitol acetal flow more than hydrophilic silica.

It has also been found that in some cases, micron size silica unexpectedly improves the flow properties of sorbitol acetal powder when the silica dosage as a percentage of the total additive composition is greater than about 10% by weight. This is desirable, and unexpected, in part because some silica manufacturers recommend using less than about two (2) weight percent silica for the purpose of aiding dust flow. See, for example, a manufacturer's web address: www.gracedavison.com/Products/Farmpc2.htm, which recommends the use of about 0.25% to about 1.0% of a hydrophilic silica, Siloid 224 FP®. The discovery in the course of the invention of this application that substantial benefits can occur above ten (10) weight percent silica (which is more than five times greater than some of the industry recommendations) is significant and unexpected.

In the practice of the invention, silica can provide flow enhancing benefits in most examples without using organic lubricating materials. Submicron sized silica desirably confers an optical reflection index relatively close to that of polyolefins, and it has been found to be very desirable in obtaining appropriate turbidity values for finished polymeric articles. Thus, the use of submicron-sized silica in sorbitol acetal compounds minimizes the amount of undesirable adverse effects on optical performance (ie, turbidity levels) when applied to a polymer or a polymeric article of manufacture. .

Some types of silica significantly improve the flow properties of sorbitol acetal compounds under appropriate conditions. Suitable conditions may include one or more of the following: (1) sufficient charge (higher than conventional dosage of silica as a flow aid), and (2) chemical nature of the silica surface (hydrophobic silica is generally better than hydrophilic silica), and (3) an appropriate particle size range (submicron particle size silica). One or more of these factors may be employed for improved flow. The invention features different additive compositions comprising a sorbitol acetal compound and a silica having at least one of the following properties: Silica may be hydrophobic as defined hereinbelow (property A). The silica may be a sub-micron sized silica component as defined hereinafter (property B). The silica may be a silica component, wherein said silica component contains a silica fraction which provides at least 1% by weight of said silica particulate additive composition, and said 1% silica fraction has particles of silica. an actual particle size of less than 1 pm (property C). The silica may be a silica component, wherein said silica component has a Mv value of less than about 20 pm and a D90 value of less than about 50 pm, and wherein the weight percentage of said silica. Silica in the additive composition is equal to or greater than about 10% (property D). Silica can have only one of these properties or properties A and B; A and C; A and D; A, B and C; A, B and D; B and C; B, C and D; B and D; C and D; or A, B, C and D in combination. Further, each of the respective additive compositions may be substantially free of organic lubricating agents.

Submicron Size Silica Component.

An additive composition may be provided in another aspect of the invention which comprises a sorbitol acetal compound and a silica component, wherein said silica component has a volumetric average diameter (Mv) value of less than about 0.10. 6 pm and a D90 value of less than about 1 pm. The "D90 value" means that the silica fraction of the additive composition in this particular embodiment of the invention is such that ninety (90)% (volume%) of the actual silica particles are less than about 1 pm in diameter. In other embodiments of the invention, a value of Mv of less than about 0.4 pm and a value of D90 of less than about 0.6 pm are employed In another embodiment, the value of Mv is in the range 0. 1 to 0.3 pm, and the D90 value ranges from 0.3 to 0.5 pm In other embodiments, the weight percent of silica in the additive composition is about 0.5% to about 30%, or from about 0.5% to about 10%, or alternatively from about 1% to about 5% A polymeric or copolymeric article of manufacture comprising such compositions may also be produced in the practice of invention.

Minimum Limit Quantity of Silica in Submicron Size Range.

In yet another aspect of the invention, a mixture of a sorbitol acetal compound and silica is disclosed. Silica in this particular embodiment may have several fractions based on particle size. However, at least one silica fraction provides more than 1% by weight of the total additive composition and also exhibits an actual particle size (Mv) of less than 1 pm. That is, it has been found that if at least 1% by weight of the total additive composition (ie DBS / silica) comprises a silica having a size of less than 1 µm, the mixture unexpectedly confers superior flow properties. Moreover, in some embodiments of the invention, such additive composition may also give a D10 value of less than about 0.5 pm; This means that 10% of the silica particles are smaller than about 0.5 pm in diameter. This silica may be hydrophobic in one embodiment. The weight percentage of silica in the additive composition may also be from about 0.5% to 30%, or alternatively from 0.5% to 10%. A polymeric article made using such an additive composition is also desirable.

Relatively Larger Silica LoadsU

In another embodiment of the invention there is provided an additive composition wherein the composition comprises a sorbitol acetal compound and a silica component, wherein the silica component has a size range Mv value of less than about 20 µm. pm and a value of D90 less than about 50 pm; and also wherein the weight percentage of silica in the total additive composition is equal to or greater than about 10%. The silica component may also provide a Mv value of less than about 10 pm, and a D90 value of less than about 25 pm, in one embodiment of the invention. The weight percent of silica in the additive composition may be from about 10% to 30% in yet another embodiment. Silica may also be hydrophobic as an option, and polymeric articles may be manufactured using such a composition.

In one embodiment, the invention features a sorbitol / silica acetal additive composition that is substantially free of organic lubricating agents, such as stearic acid metal soaps and the like. That is, unexpected and higher flow intensification can be achieved in sorbitol acetal compositions, in most cases without the use of organic lubricants and / or metal soaps, or premixes.

In practicing the invention, there is also contemplated a method of employing some of the compositions disclosed herein in the manufacture of a polyolefin, polymer, or copolymer. Formed articles, molded articles, and still others may be produced by using such additive compositions.

Powder Flow A definition of powder flow is the ability of a powder to flow. Powder flowability is usually described by a number of measurable flow properties, including cohesion force, internal friction, wall friction, shear force, tensile strength, nominal density, and permeability. Cohesive strength is one of the most important parameters used to describe the flowability of the powder. Powders with poor flow properties may develop certain flow problems, such as "bridging'1," ratholes, "and" overflow "in hopper feed equipment. Naturally occurring silicon dioxide (Si02) in various crystalline and amorphous forms Silica can also be synthesized chemically Based on the different processes employed for the synthesis of silica, various types of silica are commercially available and can be employed. depending on the particular embodiment to be obtained: (1) fumed silica, which is manufactured in a pyrogenic gas phase process by reacting silicon tetrachloride in an oxygen-hydrogen flame above 1,000 ° C to provide exceptional purity. (2) precipitated silica which is produced in a wet process by acidifying a sodium silicate solution under conditions not normally lead to a gel, and (3) silica gel, which is produced by acidifying a sodium silicate solution under conditions to lead to gel formation and to obtain a porous structure after drying. The average primary particle size of the smoked silica ranges from about 5 nm to about 50 nm, and the primary smoked silica particles form aggregates in a tightly fused structure in the size range of 100 nm to 1 pm. On the other hand, the average particle size of the precipitated silica ranges from 4 pm to about 15 pm, whereas that of silica gel, including the special form known as "airgel", may be about 4 pm or more. Hydrophilic and Hydrophobic Silicas Based on the chemical nature after surface treatment, silica is distinguished into two types in the industry: hydrophilic and hydrophobic, regardless of the particle size of the silica. Hydrophilic silica generally refers to the untreated type after chemical synthesis and exhibits an affinity for water due to the presence of silanol groups on the surface. Hydrophilic silica may be moistened with water. Without surface treatment, synthetic amorphous silica is naturally hydrophilic. Industrially sold silica is typically clearly identified by the manufacturer if it is hydrophilic or hydrophobic silica.

Hydrophobic materials are water repellent. In general, hydrophobic materials do not absorb significant amounts of water (ie less than about 1.5%) and are not immediately moistened with water. A simple water wetting test is usually used to determine if a sample is hydrophobic. Hydrophobic silica is chemically modified, and can be determined by FTIR analysis.

Commercial grades of hydrophilic silica include Degussa AG's Aerosil® and Sipernat® product lines, and Cabot's Cab-o-sil® product line. Hydrophobic silica refers to the type of silica whose surface is chemically modified by reacting the silanol groups on the surface with various silanes, silazanes and siloxanes. Hydrophobic silica cannot normally be moistened with water. Commercial grades of hydrophobic silica include the "R" series Aerosil® product line and the Degussa AG "D" series Sipernat® product line, and the "TG" series Cab-o-sil® product line , and Cabot's Nanogel® product line.

In one aspect of the invention, the additive composition comprises a sorbitol acetal compound and a hydrophobic silica. The silica filler in such an additive composition may in some cases be in the range of from about 0.5% to about 30%, or from about 0.5% to about 10%, and sometimes from about 1%. % to about 5%. A polymeric or copolymeric article may be manufactured using the additive composition. The differentiation between hydrophilic silica and hydrophobic silica can be effectively achieved by measuring different parameters such as moisture vapor adsorption isotherm, contact angle, humectability, carbon content, or infrared spectroscopy. , to name a few of them.

Silica Geometry Synthetic amorphous silica typically exists as a finely divided white powder. This powder consists of individual particles with irregular shapes and dimensions. In the dry state, it is found that the silica powders are loose agglomerates of particles. Moistening the powder with a wetting agent and applying dispersion energy facilitates microscopic evaluation of deagglomerated silica particles. These particles vary in size. Statistical methods should be employed to describe the population quantitatively.

Further examination of the silica dust using electron microscopy reveals that the particles comprise primary particles that are fused or agglutinated without backlash. The primary synthetic amorphous silica particle tends to be spherical in shape and ranges in size from about 5 to 500 nm depending on the manufacturing process used to prepare the powder. The agglomerates of these primary particles form the individual particles or aggregates. Thus, the silica dust consists of loose agglomerates of primary particle aggregates. Weak electrostatic charges as well as mechanical forces hold the cluster together. For the purpose of analysis, it is useful to disperse the powder in a liquid by stirring and applying ultrasonic energy. This will produce a liquid dispersion that is stable in size and appropriate for analysis. Various types of silica may be employed in the present invention. The examples and tables herein list various types of silica which may be used in the practice of the present invention. The practice and scope of the invention, however, are not limited solely to those types recited herein. Table 1 here lists the degrees of silica that were employed in the examples of the invention and their particle size parameters. For the purposes of this disclosure report and the claims set forth herein, submicron particle measurements are made by dynamic light scattering, and micron-sized particle measurements (greater than about 1 μιτι) are measured. by laser diffraction as indicated in Table 1. Aerosil® 300, Aerosil® R812, Aerosil® 150 and Aerosil® R972 are Smoked Silica from Degussa AG. HDK H15 is a hydrophobic fumed silica from Wacker-Chemie gmbH. Sipernat® D13 and Si-pernal® 22LS are precipitated silica from Degussa AG. Syloid® 244 is a hydrophilic silica gel from Grace Davison. However, these particular grades of silica are merely examples of the silica that may be employed, and the invention is not limited to any manufacturer or type or grade of silica. Particle Size Analysis Optical microscopy is a fundamental technique for particle size analysis. If a single particle is seen at 500 times magnification, it is possible to estimate the diameter downwards by about 0.8 pm by comparing it to a calibrated grid. Observations can also be made about the shape of the particles and whether they are transparent, absorbent, or reflective. These preliminary observations are useful for selecting an instrument to accurately measure the entire particle population in a dust sample. Ultrasonic wet sieving involves the use of electroformed precision screens with openings as small as 5 pm. Typically, a 1 gram sample of the powder is moistened with about 1 liter of dispersing fluid and the suspension is slowly filtered through the screen under vibration. The oversized particles, which are too large to pass through the screen, are dried and weighed so that a percentage value for the oversized population can be calculated. Ultrasonic wet sieving is a technique for measuring the large end of a fine particle distribution, but, like optical microscopy, is not a practical method for measuring the entire distribution so that an average or an average size of particle may be known. However, both microscopy and sieving are useful preliminary methods for determining the size range of a dust sample, so that an appropriate method can be selected.

Laser Diffraction Laser diffraction is a common technique used to measure the size distribution of a powder. A sample is dispersed in a liquid and passed through a transparent cell where it is illuminated by a laser. The laser scatter pattern is detected by an array of light-sensitive photodes. The scatter pattern is related to the size distribution of particles exposed to the laser beam, as small particles scatter monochrome light at large angles and large particles scatter it at small angles. This phenomenon is known as Fraunhofer diffraction and is the theoretical basis for commercial laser diffraction instruments. The detection range for laser diffraction instruments is as wide as 1 to 2,000 pm. Some instruments also employ Mie's theory to compensate for small particle errors to extend the lower detection range from 1 to 0.1 pm. Laser diffraction instruments measure a volume-based particle size distribution. For particle irregular shapes, the reported diameters are equivalent spherical diameters.

Data from a laser diffraction instrument is often presented as a histogram and the following statistical parameters are calculated to describe the powder size distribution.

Volumetric Average Diameter (Mv) - The volumetric weighted arithmetic mean particle diameter (also known as volumetric momentum diameter or D (4, 3). Tenth percentile (D10) - The particle diameter that corresponds to 10% of the distribution based on 50th percentile (D501 - The particle diameter corresponding to 50% of the distribution based on the cumulative volume.

90th percentile (D90) - particle diameter that corresponds to 90% of the distribution based on cumulative volume.

Dynamic Light Scattering Dynamic light scattering is another popular method used to measure the fine particle size distribution. The technique uses a diode laser to illuminate particles in a suspension to develop optical frequency shift information to measure particles ranging in size from 0.001 to 6 pm. The suspended particles are in a constant random motion (Brownian motion) as a result of interactions and collisions with the suspension fluid molecules. In Stokes-Einstein's theory of Brownian motion, the motion of particles is determined by the viscosity of the suspension fluid. Particle size can be determined from a measurement of particle movement in a fluid of known temperature and viscosity. Dynamic light scattering employs optical methods to measure particle motion. Small particles have a high speed and cause a large change in frequency, while large particles move more slowly and cause small changes in frequency in the illumination light source. The random motion of particles, measured over time, can be illuminated by a laser and used to form a distribution of optical frequency changes that can be used to calculate the size distribution of dust. The size distribution measured with dynamic light scattering is based on volume. It is common to use statistical values such as mean (Mv), tenth percentile (D 10), fiftieth percentile (D50), and ninety percentile (D90) to describe particle size distribution. Dynamic light scattering is superior to laser diffraction for measuring powders with a size range predominantly below 1 pm. Laser diffraction is a preferred method for analyzing powders containing particles greater than about 6 pm in size. Analytical Methods Both laser diffraction and dynamic light scattering techniques require that the powder be agglomerated and dispersed in a fluid. Through experimentation, it is determined that isopropyl alcohol (IPA) is a suitable wetting agent for hydrophilic and hydrophobic synthetic amorphous silica. The powder is first moistened with the shaking IPA and then dispersed with ultrasonic energy. Physical properties for IPA and silica are listed below. IPA Refractive Index - 1.38 IPA Viscosity @ 15 ° C - 2.86 cp IPA Viscosity @ 30 ° C - 1.77 cp Silica Refractive Index - 1.46 Silica Particle Format - Non- Silica Particle Opacity - Transparent More specifically, 0.75 to 1 gram of the powder is added to 30 ml filtered IPA in a 50 ml glass beaker. The suspension is stirred with a spatula until the silica dust is moistened by IPA. The beaker is sonicated using a 0.95 cm (3/8 ") diameter 750 watt ultrasonic probe for 3 minutes at 5% power adjustment. Optical microscopy and ultrasonic screening Wet light dispersions are used to evaluate the dispersion quality and estimate the particle size range in the population for each silica dust sample.The dynamic light dispersion is an appropriate method for measuring submicron silica powders in this case. The Nanotrac 150 instrument manufactured by Microtrac, Inc. is a commercially available dynamic light scattering device with a detection range of 0.0008 to 6.5 pm An IPA-dispersed silica sample is added to the Nanotrac sample cell. 150 and a measurement is made in duplicate for a time interval of 200 seconds Particle size distribution is calculated with a computer using Microtrac Flex software version 10.3.0 Laser diffraction is used here for measurements. s shown in the present specification and claims that are greater than about 1 pm, and laser diffraction is generally useful for a detection range of about 0.1 to 2000 pm. Silica powders with a significant fraction of the population larger than 6 pm are beyond the upper range of dynamic light scattering detection, while they can be readily analyzed by laser diffraction. The Microtrac S3500 is a commercially available laser diffraction instrument manufactured by Microtrac, Inc. The instrument uses a three-laser system and an external sample circulation system to generate a volume-based size distribution. Silica powders are analyzed by first dispersing in IPA using an ultrasonic probe and then transferring a representative sample of the dispersion to the IPA-containing sample circulation system. The diluted suspension circulates through a sample cell where particles are illuminated by laser light. The diffraction pattern for three 30-second time intervals is recorded and the size distribution is calculated by a computer using Microtrac Flex version 10.3.0 software.

In addition to the normal volume-based statistical parameters, an average number-based particle size (Mn) is calculated and recorded. Mn gives a larger weight to smaller particles in the distribution and is shown with the volume-based average particle size for comparative purposes.

Sorbitol Diacetals (Sorbitol Acetal Compounds) Clarifying agents of interest for use with the particular silica described herein include sorbitol and xylitol diacetals having the general formula (I) wherein R1, R2, R3, R4, Rs, Re , R 7, Re, R 9 and R 10 are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxy group carbonyl having 1 to 4 carbons, a halogen atom, a hydroxy group, an alkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbon atoms, or a 4 or 5 membered alkyl group forming a carbocyclic ring with the adjacent carbon atoms of the original unsaturated ring; en represents 0 or 1. Of particular interest are those clarifiers where n is 1 and R 1, R 2, R 3, R 4, R 6, R 6, R 7, Re, R 6 and R 10 are selected from C 1-4 alkyl, chloro, bromo thioether is a 4-membered alkyl group that forms a carbocyclic ring with the adjacent carbon atoms of the original unsaturated ring. Examples of specific clarifiers include: dibenzylidene sorbitol, bis (p-methylbenzylidene) sorbitol, bis (o-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol, bis (3,4-dimethylbenzylidene) sorbitol, bis ( 3,4-diethylbenzylidene) sorbitol, bis (5 ', 6', 7 ', 8, tetrahydro-2-naphthylidene) sorbitol, bis (trimethylbenzylidene) xylitol, and bis (trimethylbenzylidene) sorbitol.

Also within the scope of the present invention are compounds made from a mixture of aldehydes, including substituted and unsubstituted benzaldehydes, and still others.

Clarifying agents of interest also include sorbitol and xylitol diacetals which have a non-hydrogen substituted on the first carbon (i.e., C-ι) of the sorbitol chain, as shown in general formula (II): where R may be selected from the group consisting of: alkenyls, alkyls, alkoxy, hydroxylalkyls, and haloalkyls, and their derivatives; R1, R2, R3. R4, R5, Re, R7, Rs, R9 and R10 are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms. carbon, an alkoxycarbonyl group having 1 to 4 carbons, a halogen atom, a hydroxy group, an alkylthio group having 1 to 6 atoms, an alkylsulfoxy group having 1 to 6 carbon atoms, or an alkyl group of 3 or 5 members forming a carbocyclic ring with the adjacent carbon atoms of the original unsaturated ring; and n is 0 or 1. Of particular interest are those clarifiers where R is methyl, ethyl, propyl, butyl, allyl, or crotyl, and R1, R2, R3, R4, Rs, Re, R7, Re, R9 and R10 are selected. between C 1-4 alkyl, chlorine, bromine, thioether and a 4-membered alkyl group that forms a carbocyclic ring with the adjacent carbon atoms of the original unsaturated ring.

Examples of specific clarifiers which may be mixed with silica and employed in the practice of the invention include: 1,3: 2,4-bis (4-ethylbenzylidene) -1-allyl sorbitol, 1,3: 2,4-bis (3'-methyl-4'-fluoro-benzylidene) -1-propyl sorbitol, 1,3: 2,4-bis (5,6 ', 7', 8'-tetrahydro-2-naphthaldeidobenzylidene) -1-allyl-xylitol, bis-1,3: 2-4- (3 ', 4'-dimethylbenzylidene) -1-methyl-sorbitol, and 1,3: 2,4-bis (3', 4'- dimethylbenzylidene) -1-propyl xylitol.

A sorbitol acetal clarifier that can be employed is Millad® 3988, which is manufactured and distributed by Milliken & Company of Spartanburg, South Carolina. Its chemical identity is 1,3: 2,4-bis (3, 4-dimethylbenzylidene) sorbitol, and is known as "DMDBS". Millad® 3988 used in this specification is commercial grade, which is manufactured with a grinding step through an air jet mill to obtain the ultrafine particle size of the particle (d97 of 30 microns or less and a average particle size of 15 microns or less) which is useful for achieving its full clarification power.

A surprising finding in the invention is that there is "snag" or synergy between the silica particle and the primary sorbitol acetal particle, which is unexpected.

A second example, Millad® 3940, is manufactured and distributed by Milliken & Company of Spartanburg, South Carolina. Its chemical identity is 1,3: 2,4-bis (4-methylbenzylidene) sorbitol, and is sometimes known as MDBS. Millad® 3940 used in this descriptive report is commercial grade. The practice and scope of the present invention, however, are not limited to these two examples.

Thermoplastic Polymers and Copolymers Polyolefins are widely used in article applications including household containers, vials, cups, syringes, tubing, films, and more, through various processing methods such as injection molding, blow molding with extrusion, thermoforming, and casting. In many applications, the transparency or clarity of such plastic parts is desired. Clarifiers such as Millad® 3988 are used in these applications to give plastic articles the desired optical properties. Typical polymers using clarifying or nucleating agents include polypropylene homopolymer (HPP), randomized polypropylene copolymer (RCP) and polypropylene impact copolymer (ICP). Millad® 3988 also clarifies some polyethylene resins, such as linear low density polyethylene (LLDPE), low density polyethylene (LDPE), and high density polyethylene (HDPE). The polytolefin employed in the examples in this case is Profax SA849, which is a random polypropylene sferipol copolymer of about 12 MFR (g / 10 min). The practice and scope of the invention, however, are not limited to PCR SA849, or even to any particular polymer or polyolefin. Many other grades of polyolefin can be successfully employed in the practice of the invention.

Flow Measurement To quantify the effect of silica on reducing the cohesive force of DMDBS, and thereby improving the flowability of the powder, Jenike-Schulze ring shear tests were performed to determine the cohesion force of the following examples according to ASTM standard D6773-02. The data shown in the tables and figures related to the examples indicate the relationship between the cohesion force of the powders as a function of the consolidation pressure. Typically, as a powder is compressed, its cohesive force increases. The improved flowability in a given powder formulation is shown by a lower line on the graph compared to the comparative control (see figures 5 to 9).

Comparative Example 100% DMDBS is used as a comparative example for all example games. Your cohesion force data is listed in the following tables. This example is performed by stirring DMDBS (50 g) at room temperature for 20 seconds when using a consumer grade food processor that has a bowl with a diameter of 11 cm and a height of 10 cm. The food chopper has a sharp S-shaped blade with a diameter of 10 cm and rotates at about 1,500 rpm when rotating. LOAD LEVELS OF SILICA HYDROPHILIC SILICA MIXTURES USING MICRON SIZE SILICA Examples 1-1 to 1-5 Table 2 and Figure 5 illustrate the cohesive strength data of formulations containing DMDBS and hydrophilic micron size silica -! Syloid® 244 (Mv = 10.8) (micron size silica range) at a constant total mass of 50 g and various relationships between them. Each formulation is mixed at room temperature for 20 seconds using a consumer grade food processor that has a bowl with a diameter of 11 cm and a height of 10 cm.

Table 2: Cohesive strength data of DMDBS and Syloid® 244 hydrophilic powder formulations (hydrophilic, micron size) Comparison can be seen between the cohesion force of various DMDBS / silica mixtures for micron size silica . It can be seen from Table 2 that the cohesive force decreases significantly when more than about 10 weight percent of such silica is employed, which is highly desirable. The decrease in cohesive force corresponds to an increase in the flowability of the additive composition.

Examples 1-2, 1-3, 1-4 and 1-5 show that for micron size silica, weight ratios of about 10 to about 30 weight percent perform particularly well, reducing cohesive force, and thus increased flow properties. Thus, this example illustrates that charge levels in the range of about 10 to 30% are completely useful. A load level of from about 10 to about 20 percent performs very well, as shown by the lower lines in figure 5 (Examples 1-3 and 1-4). HYDROPHICAL SILICON VERSUS HYDROPHILIC: EFFECTS WHEN MICRON SIZE SILICON IS USED

Examples 2-1 and 2-2 Table 3 and Figure 6 illustrate the cohesive strength data of formulations containing DMDBS and varying degrees of micron size silica at a constant total mass of 50 g and a constant ratio of 97: 3 between DMDBS and the corresponding silica grade. Each formulation is mixed at room temperature for 20 seconds using a consumer grade food processor that has a bowl with a diameter of 11 cm and a height of 10 cm.

The data generated and shown in Table 3 show that for this silica charge in question (3 percent), a hydrophobic silica results in a lower cohesive strength value (higher flowability) than hydrophilic silica (compare 26 to 29). , and 48 to 54, below). This is seen graphically in Figure 6, where the lowest line in the graph represents the hydrophobic example, 2-1.

Table 3: Cohesive strength data of DMDBS powder formulations and micron size hydrophobic or hydrophilic silica grades HYDROPHYLIC SILICA VERSUS HYDROPHOLIC SILICON: EFFECTS ON SUBMITRON AND MICRON SIZE RANGES Examples 3-1 and 3-2 Table 4 and Figure 7 illustrate the cohesive force data of formulations containing DMDBS and varying degrees of silica of submicron and micron sizes at a constant total mass of 50 g and a constant 97: 3 ratio between DMDBS 7 and silica grade. corresponding. Each formulation is mixed at room temperature for 20 seconds using a consumer grade food processor that has a bowl with a diameter of 11 cm and a height of 10 cm. The two formulations (Examples 2-1 and 2-2) containing DMDBS and micron size silica grades are also included herein for comparison purposes.

Table 4. Cohesive Strength Data of DMDBS Powder Formulations and Submicron Size or Micron Size Silica Degrees The above data shows that silica in the submicron size range generally performs better than silica micron size. Examples 3-1 and 3-2, as seen in Figure 7, confer the lowest cohesive force, and thus the greater flowability of the additive composition.

In addition, for micron sizes (i.e. 2-1 and 2-2), hydrophobic silica (2-1) performed better than hydrophilic silica (22) as shown at the top of Figure 7 .

LOAD LEVEL COMPARISONS FOR HYDROPHONIC SUBMICON SIZE SILICA PARTICLES

Examples 4-1 to 4-5 Examples 4-1 to 4-5 (see Figure 8) are intended for larger pilot scale experimentation to evaluate the feasibility of applying the invention, and to compare the load levels of silica to the submicron size silica particles in the mixture. Table 5 and Figure 8 illustrate the cohesive strength data of formulations containing DMDBS and hydrophobic hydrophobic submicron sized silica (a hydrophobic smoked submicron size silica) at a constant total mass of 10 kg and five different relationships between them. Each formulation was mixed at room temperature for 30 seconds using a Lodige Model FKM 130 batch mixer equipped with Becker paddles and high speed choppers.

Table 5: Force cohesion data of DMDBS and Aerosil® R972 (hydrophobic, submicron size) powder formulations of the pilot scale mixer The load levels employed were between 1% and 5%. The results indicate that the 5% load level was higher, and generally, as the load levels increased by 1 to 5 percent, the cohesive force tended to decrease (which correlates with better results, ie (an improved amount of fluidity). Figure 8 shows that improved results (i.e. the bottom line) of higher flowability (lower cohesive force) are apparent at about 5% load for this example of silica in the submicron size range. MDBS NUCLEATING AGENT: Examples 5-1 and 5-2 Examples 5-1 through 5-2 employ MDBS, bis (p-methylbenzylidene) sorbitol, sold by Milliken & Company as a brand nucleating agent Millad® 3940 (which is also known as "MOBS11). Other sorbitol acetal compounds could be employed equally well in the practice of the invention, and the invention is applicable for essentially any sorbitol acetal compound. Table 6 and Figure 9 illustrate the cohesive strength data of formulations containing Aerosil® R972 hydrophobic submicron size silica-MDBS at a constant total mass of 50 g in two different ratios.Each formulation is mixed at room temperature for 20 seconds using a consumer grade food processor that has a bowl with a diameter of 11 cm and a height of 10 cm.

The results indicate that 3% silica substantially increased the cohesive properties of the MDBS / silica mixture, reducing cohesion strength, and thereby improving flowability.

Table 6: Cohesive strength data of MDBS and Aerosil® R972 powder formulations (hydrophobic. Submicron size) Turbidity Measurements Examples 6-1 and 6-15 To examine whether incorporation of silica into DMDBS powder would have The negative impact on turbidity of the polymeric articles produced using such a mixture, various formulations containing DMDBS and various silica classes in different ratios were tested for their clarification function on a degree of random polypropylene copolymer (as shown in Table 7). The results below indicate that the turbidity levels for the silica samples are lower than the control sample that did not use silica (ie, Example 6-1), which shows no undesirable effect on turbidity by the use of silica. indicated silica grades. The standard processing condition comprises the following steps: a) each polymer composition is composed of random polypropylene (12 MFR) cup-polymer flakes 1,000 g, Irganox® 1010 (primary anti-oxidant, available from Ciba) 0.5 g (500 ppm), Irgafos® 168 (secondary anti-oxidant, available from Ciba) 1 g (1,000 ppm), calcium stearate (acid remover) 0.8 g (800 ppm), DMDBS 2 g (2,000 ppm), and silica at various loads (see Table 7 for silica grades and usage levels); b) mixing all components in a high intensity mixer at room temperature for 1 minute; c) combining the mixture using a single screw extruder at about 230 ° C; d) molding the combined resin into 2 x 3 x 0.05 inch plates at a melting temperature of about 230 ° C; e) at least 12 plates are collected for turbidity reading in accordance with ASTM D1003-92 when using a BYK Gardner haze-gard plus turbidity meter; and f) the sample plates are subjected to white spot detection under an Olimpus BX51 vertical light microscope.

Table 7: Optical Performance of Polypropylene Formulations Containing 2,000 ppm DMDBS versus Silica Degree and Load Technical Conclusions There are at least three independent key factors that dominate the potential for improving silica flowability for sorbitol acetal compounds. The inventions identified herein correspond in some cases to findings that relate to such factors.

Important factors in the flow performance of silica / sorbitol acetal additive compositions are: 1) the load (percent by weight) of silica in the additive compositions; 2) the hydrophobic capacity of the silica employed; and 3) the particle size of the silica particles employed in the additive compositions.

Load As shown in Table 2 and Figure 5, Syloid® 244 does not improve the flow properties of DMDBS powder additive mixtures until its dosage is higher than about 10% by weight of the total additive formulation. composition. This is somewhat unexpected, as silica manufacturers in the industry recommend about 2% silica when silica is employed as a granular or powdered flow aid. Thus, a level of 10% or higher load is unexpected.

Hydrophobic Capacity Another important factor in improving flow is the chemical nature of the silica surface used. As suggested in Table 3 and Figure 6, hydrophobic silica (Sipernat® D13) works much better than hydrophilic silica (Sipernat® 22LS) (see Table 1). Together with the results of Table 2 and Figure 5, it can be concluded that unusually high silica fillers can be lowered to some extent if the chemical nature of the correct silica surface is chosen (hydrophobic capacity). Sipernat® D13 works at a 3% by weight load (even higher than the conventional load) comparable to Syloid® 244 at a 20% by weight load. While not wishing to be limited by the mechanism, it is believed that there may be greater compatibility between the surface of the DMDBS particle and the surface of the hydrophobic silica particle, which may lead to a more effective flow improvement for silica grades. hydrophobic. In general, hydrophobic silica exhibits improved performance compared to hydrophilic silica, especially at submicron fillers.

Particle Size Another key factor controlling the flow potential for additive compositions of silica sorbitol acetal compounds is the particle size of the silica employed. Table 4 and Figure 7 demonstrate the best flow performance of two different grades of smoked silica. The fumed silica is of a submicron size, and significantly smaller than the micron size silica. The fumed silica performed well in the practice of the invention.

A comparison was made between these two grades of silica, both of which are in the submicron size range, but have a different surface chemical nature (Aerosil® R972 is hydrophobic, and Aero-sil® 300 is hydrophilic). Both significantly improve DMDBS powder flow properties. They improve DMDBS flow properties significantly better than micron size silica grades (Sipernat® D13 and Sipernat® 22LS).

Pilot Scale Experimentation To optimize the process and verify findings, a pilot scale experimentation using an industrial mixer was performed. The cohesion force data confirmed the findings described above. The silica DMDBS formulation has significantly better flow properties than silica-free DMDBS. At the same time, the hydrophobic surface and submicron size of Aerosil® R972 (as an example) results in a much lower effective load than Syloid® 244 (Table 2 and Figure 5). It is understood by one skilled in the art that the present discussion is a description of exemplary embodiments only, and is not intended to limit the broader aspects of the present invention. The invention is shown by way of example in the appended claims, but is not limited to to such examples.

Claims (10)

1. Additive composition, characterized in that it comprises: (a) a sorbitol acetal compound, and (b) a silica component, wherein the weight percentage of the silica component in the additive composition is between 0.5%. 30% and the silica component is one of the following silica components (i) to (iv): (i) wherein said silica component has a Mv value of less than 0.6 pm and a D90 value of less than at 1 pm; or (ii) wherein said silica component contains a silica fraction, and said silica fraction contains at least 1% by weight of particles having a size of less than 1 pm; or (iii) wherein said silica component has an Mv value of less than 20 pm and a D90 value of less than 50 pm; and the percentage by weight of silica in the additive composition is 10% or greater; or (iv) wherein the silica component is hydrophobic. Composition according to Claim 1, characterized in that said silica component (i) has a Mv value of less than 0.4 pm and a D90 value of less than 0.6 pm. Composition according to Claim 1, characterized in that the percentage by weight of silica (i) in the additive composition is 1% to 5%. Composition according to Claim 1, characterized in that the silica component (ii) has a D10 value of less than 0.5 pm. Composition according to Claim 1, characterized in that the weight percentage of silica (ii) in the additive composition is 0.5% to 10%. Composition according to Claim 1, characterized in that the silica component (iii) has an Mv value of less than 10 pm and a D90 value of less than 25 pm. Composition according to any one of Claims 1 to 6, characterized in that said silica is hydrophobic. 8. Additive composition of nucleating agent which is free of organic lubricating agents, said additive composition being characterized in that it consists essentially of: (a) a sorbitol acetal compound, and (b) a component hydrophobic silica component, said hydrophobic silica component having: a Mv value of less than 20 pm, and a D90 value of less than 50 pm, and wherein the weight percentage of the hydrophobic silica component in the additive composition is 1% to 10%. A polyolefin-based composition, characterized in that it comprises: (a) a polyolefin, and (b) the composition as defined in claim 1, wherein the silica is a silica component (i) or a silica (iv). A method for producing a nucleated copolymer or polymeric composition, characterized in that said method comprises the steps of: providing a polymer or copolymer; providing an additive composition selected from the group consisting of: (i) an additive composition comprising: a sorbitol acetal compound and a silica component, the silica component having a Mv value of less than 0.6 pm and a D90 value less than 1 pm; and the weight percentage of the silica component in the additive composition is between 0.5% and 30%. (ii) an additive composition comprising a sorbitol acetal compound and a silica component; wherein said silica component has a Mv value of less than 20 pm and a D90 value of less than 50 pm; and the weight percentage of silica in the additive composition is 10% or greater, (iii) an additive composition having a sorbitol acetal compound and a hydrophobic silica, wherein the weight percentage of said silica in the additive composition is 0 , 5% and 30%; and feeding and dispersing said additive composition in said polymer or copolymer to form a nucleated polymer or copolymer.